PICK SEA FTs: add @tag("channels") to ChannelsFunctionalTest subclasses — CI fix

- PickSeaAsyncTransitionTest + PickSeaDealTest extend ChannelsFunctionalTest
  (ChannelsLiveServerTestCase), which spawns a child process; daemonic parallel
  workers cannot have children → setUpClass AssertionError in CI test-FTs stage
- @tag("channels") routes them to the non-parallel test-two-browser-FTs stage

Code architected by Disco DeDisco <discodedisco@outlook.com>
Git commit message Co-Authored-By:
Claude Sonnet 4.6 <noreply@anthropic.com>

src/functional_tests/test_room_sea_select.py

@@ -1,5 +1,6 @@
 """Functional tests for the PICK SEA overlay — Celtic Cross draw."""
 
+from django.test import tag
 from django.urls import reverse
 from django.utils import timezone
 from selenium.webdriver.common.by import By
@@ -35,6 +36,7 @@ def _make_sky_confirmed_room(live_server_url, user, earthman):
     return room, seat
 
 
+@tag("channels")
 class PickSeaAsyncTransitionTest(ChannelsFunctionalTest):
     """After sky confirm, PICK SEA overlay appears without a page refresh."""
 
@@ -180,6 +182,7 @@ def _make_sea_ready_room(earthman):
     return room, gamer, seat, char
 
 
+@tag("channels")
 class PickSeaDealTest(ChannelsFunctionalTest):
     """PICK SEA deck stacks, OK btn interaction, card draw, and LOCK HAND."""